Changes in the activity of single neurons will be recorded from sites in the brain stem and basal ganglia in an attempt to determine their neuronal organization. Activity altered by drugs with actions in these sites such as direct and indirect acting dopamine agonists (e.g., amphetamine) and dopamine antagonists (e.g., haloperidol) will be sought in an effort to clarify the neuronal and synaptic mechanisms of action of such agents. Statistical analysis of spontaneous neuronal spike trains will be utilized to characterize changes in neuronal firing rates, patterns and to infer the existence of functional interconnections between neurons using the methods for recording spontaneous neuronal activity in animals chronically implanted with microelectrodes will be developed with an effort to use EM transmission rather than conventional cable connections between the subject and recording equipment. Once developed, statistical analyses of spontaneous neuronal spike trains in this preparation will be used to characterize changes in neuronal activity as described for experiments using acute preparations. BIBLIOGRAPHIC REFERENCES: Paden, C., Wilson, C., and Groves P. Amphetamine-induced release of dopamine from the substantia nigra in vitro. Life Sciences, 19, 1499-1506, 1976. Groves, P., Young, S.J., and Wilson, C.J. Self-inhibition by dopaminergic neurons: Disruption by (plus or minus) -alpha-methyl-para-tyrosine pretreatment or anterior diencephalic lesions. Neuropharmacology, 15, 755-762, 1976.